<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>

<body>
    <button id="btn">点击获取信息</button>
    <script>
        const btn = document.querySelector('#btn')
        btn.addEventListener('click', () => {
            const p = new Promise((resolve, reject) => {
                const xhr = new XMLHttpRequest()
                xhr.open('GET', 'http://127.0.0.1:3007/api')
                xhr.send()
                xhr.onreadystatechange = () => {
                    if (xhr.readyState === 4) {
                        if (xhr.status >= 200 && xhr.status < 300) {
                            resolve(xhr.response)
                        } else {
                            reject(`获取失败${xhr.status}`)
                        }
                    }
                }

            })
            p.then(value => {
                console.log(value);
            }, reason => {
                console.log(reason);
            })
        })
    </script>
</body>

</html>